MXPA97007067A - Two-component polyamide / polyolefine fibers, novedosas and methods for elaborating - Google Patents

Abstract

The present invention relates to novel bicomponent fibers, such as fibers for the carpet surface, having a polyamide domain spun by co-melting with a polyolefin domain. Preferred fibers are bicomponent core-sheath fibers having the polyamide domain as the sheath and the polyolefin domain as the core. The core comprises less than 30% by weight of the fiber and more preferably less than 25% by weight. This bicomponent fiber has desirable physical properties, which are comparable with the fibers that are formed of 100% polyamide. The polyolefin core can optionally include one or more inert organic filler materials to further reduce the cost of the material for fib production.

Description

TWO-COMPONENT POLYAMIDE / POLYOLEPHINE FIBERS, NOVELTY AND METHODS TO MANUFACTURE THEM Cross-referencing with related applications This request may be considered related to US Patent Application Serial No., (File No. 1005-91) of the public domain, filed on the same date hereof, the entire content of which is is expressly incorporated herein by reference. FIELD OF THE INVENTION The present invention relates generally to the field of synthetic fibers. More particularly, the present invention relates to synthetic two-component fibers that preferably have a concentric core-sheath structure. In particularly preferred forms, the present invention is incorporated into the two-component multi-lobed fibers having a polyamide sheath that completely surrounds a concentric core formed of a polyolefin (e.g., polypropylene, polyethylene or the like) which may optionally include an inert charge material dispersed in you.

BACKGROUND OF THE INVENTION Polyamide has been widely used as a synthetic fiber. Although its structural and mechanical properties make it attractive for use in capacities such as carpet manufacturing, it is nonetheless relatively expensive. Therefore, it would be desirable to replace a portion of the polyamide fibers with a core formed of a relatively low cost non-polyamide material. However, replacement of a part of a 100% polyamide fiber with a core part of a relatively less expensive non-polyamide material can affect the mechanical properties of the fiber to a degree where it is no longer useful in its application. proposed end use (for example, as a fiber for carpets).

Recently, U.S. Patent No. 5,549,957 has proposed multi-lobed composite fibers having a nylon sheath and a core of a fiber-forming polymer which may be, for example, "of another specification" or of the claimed polymers. (Column 4 line 6-8). The core can be polypropylene, polyethylene terephthalate, high density polyethylene, polyester or polyvinyl chloride. (Column 4, lines 17-20). The core is covered with a virgin nylon sheath that constitutes between 30 to 50% by weight of the core / sheath fiber. (Column 3, line 65-67). U.S. Patent No. 4,297,413 to Sasa i et al. (all the content of which is expressly incorporated in the present reference) describes bicomponent sheath-core mixed yarn adapted for use as fishing line. According to this patent, the core is a preoriented polyolefin filament which is covered with a sheath formed of a crystalline resin different from the polyolefin core. (Column 2, line 15-21). The sheath can be applied over the preoriented polyolefin core using a conventional spider nozzle. (Column 2, line 49-54).

SUMMARY OF THE INVENTION In its extension, the present invention refers to novel bicomponent fibers useful as fibers for the surface of the carpet having a co-molten yarn of the polyamide domain with a polyolefin domain. Most preferably, the bi-component fibers are concentric sheath-core structures having a polyamide sheath and a polyolefin core, wherein the core contains less than 30% by weight of the fiber and more particularly less than 25% by weight. These bicomponent fibers have desirable physical properties that are comparable with the fibers formed of 100% polyamide. The polyolefin core may optionally include one or more inert organic filler materials to modify the total density of the fiber (compensating for the low density of the polyolefin core compared to the polyamide sheath).

These and other aspects and advantages of this invention will become clearer upon careful consideration of the following detailed description of the preferred exemplified embodiments thereof.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS As used herein and in the accompanying claims, the term "fiber" includes fibers of extreme or indefinite length (filaments) and short length fibers (fibers). The term "yarn" refers to a continuous strand or bundle of fibers.

The term "fiber former" is understood to refer to linear partially crystalline, at least partially oriented polymers which are capable of being formed into a fibrous structure and having a length of at least 100 times their width and are capable of of being stretched without breaking at least about 10%.

The term "bicomponent fiber" is a fiber having at least 2 different transverse domains respectively formed of different polymers. The term "fiber Two-component "in this way it is proposed to include the concentric and eccentric sheath-core fiber structures, the symmetrical and asymmetric side-by-side fiber structures, the island fiber structures in the sea and the triangular wedge fiber structures. according to the present invention are the concentric sheath-core bicomponent fiber structures having a polyamide sheath and a polyolefin core, thus, the following description will be directed to this preferred embodiment, however, the present invention is also applicable to the other two-component fiber structures having a polyamide domain and a polyolefin domain.

By the term "linear polymer" it is meant that it comprises polymers having a linear chain structure where less than about 10% of the structural units have chains and / or side branches.

Preferred polyamides useful for forming the sheath of the bicomponent fibers of this invention are those that are generally known by the term "nylon" and are long chain synthetic polymers containing amide bonds (-CO-NH-) throughout of the main polymer chain. The melt-spinnable fiber-forming polyamides suitable for the sheath of the sheath-core bicomponent fibers according to this invention include those obtained by polymerization of a lactam or an amino acid, or those polymers formed by the condensation of a diamine and a dicarboxylic acid. Common polyamides useful in the present invention include nylon 6, nylon 6/6, nylon 6/9, nylon 6/10, nylon 6T, nylon 6/12, nylon 11, nylon 12 and copolymers thereof or mixtures thereof. The polyamides can also be copolymers or nylon 6 or nylon 6/6 and nylon salts obtained by the reaction of a dicarboxylic acid component, such as terephthalic acid, isophthalic acid, adipic acid or sebasic acid with a diamine such as hexamethylenediamine, metaxylenediamine, or 1,4-bis-aminomethylcyclohexane. Preferred are poly-e-caprolactam (nylon 6) and polyhexamethylene adipamide (nylon 6/6). More preferably nylon 6.

It is important to note that the core of the fibers according to this invention is a linear fiber-forming polyolefin. Polypropylene and linear polyethylene are particularly preferred.

The core will represent less than about 30% by weight of the fibers according to the invention, with the sheath representing more than about 70% by weight. More preferably, the core will be less than about 25% by weight of the fibers according to the invention, the sheath being present in the fibers in an amount greater than about 75% by weight. In this way, the weight relationships of the sheath to the core in the fibers of this invention may be in the range from about 2.3: 1 to about 10: 1, with a ratio of greater than about 3: 1 being particularly preferred. The yarns formed from the fibers according to the invention will have desirable properties such as less than about 75% thermoset shrink compared to yarns formed from 100% polyamide fibers.

The core may optionally include an inert particulate filler material dispersed therein. The filler material can have an average particle size that is small enough to pass through the polymer filter in the spinneret without affecting the filter pressure. In this regard, particulate fillers having a particle size in the range between about 0.05 to 1.0 microns and preferably less than about 0.5 microns may be employed. When used, the filler material can be blended into a melt of the polyolefin resin of the core before being spun by melting with the polyamide shell resin using conventional melt blending equipment. In this way, for example, the loading material can be introduced through a side arm associated with an extruder that melts the polyolefin and mixes the filler material introduced therein upstream of the spinneret.

Suitable particulate fillers include calcium carbonate, alumina trihydrate, barium sulfate, calcium sulfate, mica, carbon black, graphite, kaolin, silica, talc, and titanium dioxide. Calcium carbonate is particularly preferred.

The sheath-core fibers are spun using conventional fiber-forming equipment. In this way, for example, the molten fluids separated from the sheath and core polymers can be fed to a row of the conventional core sheath as described in U.S. Patent Nos. 5, 162, 074, 5 , 125, 818, 5,344, 297, 5, 444, 884 (the total content of each patent is expressly incorporated herein by reference) wherein the molten fluids combine to form extruded, multi-lobed fibers (e.g., tri-, tetra-, penta- or hexalobulares) that have sheath and core structures. Preferably, the fibers have a tri-lobed structure with a modification ratio of at least about 1-4, more preferably between 2 and 4. In this sense, the term "modification ratio" means the ratio R? / R2 where R2 is the radius of the largest circle that is completely within a cross section of the fiber, and Ri is the radius of the circle circumscribing the cross section.

The extruded fibers are tempered, for example with air to solidify the fibers. The fibers can then be treated with a finish comprising a lubricating oil or a mixture of oils and antistatic agents. The fibers thus formed are then combined to form a skein of yarn which is then rolled into a suitable package. At a later stage, the yarn is stretched and textured to form a continuous rolled fiber yarn (FCE) suitable for making the tassels on the carpets. A more preferred technique involves the combination of the extruded or spun fibers in a yarn, then the stretching, texturing and wrapping in a packet all in one step. This FCE step processing method is generally known in the art as spin-stretch-texture (HET). Nylon fibers for carpet manufacturing purposes have linear densities in the range of about 3 to about 75 denier / filament (dpf) (denier = weight in grams of a single fiber with a length of 9000 meters). A more preferred range for carpet fibers is from about 15 to 25 dpf. The FCE threads can go through several processing steps well known to those skilled in the art. For example, to produce carpets for floor covering applications, FCE yarns are usually formed into tassels in a primary and flexible backing fabric. Materials for primary background fabric it is usually selected from jute-woven, woven polypropylene, cellulosic non-woven fabrics and nylon, polyester and polypropylene nonwovens. The primary bottom fabric is then coated with a suitable latex material such as a conventional styrene-butadiene (EB) latex., a polymer of vinylidene chloride or copolymers of vinyl chloride-vinylidene chloride. It is common practice to use filler materials such as calcium carbonate to reduce latex costs. The final step is to apply a secondary backing fabric, usually a woven jute or synthetic fabric such as polypropylene. Preferably, carpets for floor covering applications will include a woven polypropylene primary bottom fabric, a conventional EB latex formulation and a secondary bottom fabric for woven polypropylene or woven jute carpets. The latex EB may include filler material such as calcium carbonate and / or one or more of the hydrate materials listed above. Although the above explanation has emphasized the fibers of this invention formed into bulky continuous fibers for the purpose of making carpet fibers, the fibers of this invention can be processed to form fibers for a variety of textile applications. In this sense, the fibers can be curled or otherwise textured and then cut to form random lengths of short fibers having individual fiber lengths ranging from about 3.8 to about 20.32 cm (from lVt to about 8 inches). The fibers of this invention can be dyed or colored using conventional techniques for coloring fibers. For example, the fibers of this invention can be subjected to an acid staining bath to achieve the desired coloration of the fiber. Alternatively, the nylon sheath can be colored in the melt prior to the formation of the fiber (i.e., dyed in solution) using the conventional pigments for this purpose. A greater understanding of this invention will be obtained from the following non-limiting examples that illustrate the specific embodiments thereof.

Examples The physical properties of the samples were obtained from the following example using the following test procedures: Measurement of linear density (denier): The linear density of the fibers was determined using ASTM D1059, where the length of the yarn used was 90 cm.

Shrinkage (autoclave or Superba): The shrinkage was calculated using the linear densities, before and after the thermosetting in autoclave or Superba, of the thread by means of the formula: »- * Ofter-Oantes / O afterwards where dantes and after are respectively the linear densities before and after thermosetting in autoclave or Superba. 0 Wear on the Vetterman drum: The test on the Vetterman drum simulated wear according to ASTM D5417. The degree of wear exhibited by the samples is determined by a visual classification in relation to the photographic wear standards of the Carpet and Rug Institute 5 (SRI reference scale available from SRI P.O. Box 2048, Dalton Georgia, USA). Each of the common types of carpet manufacture has a corresponding series of photographic examples of woven and non-woven samples. Wear levels are from 5 to 1, where 5 represents 0 no visible wear and 1 represents considerable wear.

Shrinkage in boiling water: Shrinkage in boiling water was determined using ASTM D2259-1987. 5 Conservation of hair height: Hair height preservation was measured on carpet samples exposed to traffic using a compressor, manufactured by Schiefer, with a load of 0.5 psi and a surface area of 90 square cm (1 square foot) ) per pressure foot. First the height of the carpet sample not exposed to traffic was measured at 12 places within the carpet sample, using a template to ensure that the sample locations were measured after exposure to traffic. The samples were left for 24 hours after exposure and then subjected to vacuum. After an additional 48 hours were left, the hair height of the carpet sample exposed to traffic was determined. The average of the final 12 measurements was divided by the average of the original 12 measurements and multiplied by 100 to give the percentage of hair height retained. The tests and measurements were made at 21 ° C (70 ° F) and 65% relative humidity.

Static compression: Static comprehension was determined by testing 4 samples of the material. The initial hair height of each carpet sample was determined under a load of 0.5 psi using the compresometer and the methods as described above and determining the retention of the hair height. The carpet was compressed for 24 hours at 50 psi. The compression force was then removed and the carpet was subjected to vacuum and allowed to recover without load for another 24 hours, after which the final readings were made. The result was the average of the 4 samples reported as one percent of the original height of the hair. The tests and measurements were made at 21 ° C (70 ° F) and 65% relative humidity.

EXAMPLE 1 (comparative) Extrusion of nylon 6 (available from BASF Corp, as Ultramid® BS-700F) was done at 270 ° C in a modified trilobal cross section -58 filaments, 1100 denier for the total yarn. The winding speed was 2400 meters per minute. The yarn was processed in a one-step method in which the yarn was extruded, stretched and textured in a continuous process. Two of these threads were then combined in a cable rewind operation. The wired wire had a torque of 3.75 turns per inch torsion "S". Skeins of wired wire were hot-hardened in an autoclave with water using a temperature cycle of 132 ° C (270 ° F) -110 ° C (230 ° F) -132 ° C-110 ° C-132 ° C. The yarn was then formed into tassels in a 1/8 gauge carpet tassel machine at a hair height of 1.43 cm and a weight of 992 g of fiber frontal by 0.836 square meters of carpet. The carpet was then stained to a light brown color in a range of continuous staining. Latex and a secondary bottom fabric were applied to this carpet. The physical properties of the yarn and the carpet are indicated below in Table 1.

Example 2 (invention) The nylon 6 resin described in Example 1 was extruded at 270 ° C. The polypropylene was extruded in an extruder at an exit temperature of about 220 ° C. These polymers were combined in a sheath of bicomponent sheath-core fiber. The polypropylene resin was nicked in the 58-filament core using thin etched plates such as those described in U.S. Patent 5,344,297 to Hills and U.S. Patent 5,445,884 to Hoyt et al (the total content of each patent is expressly incorporated herein). as reference) . The combined molten polymer fluids were passed through the same trilobal capillary and orifice as in Example 1. The caliper of the two polymer fluids was controlled to produce an 85:15 weight ratio of the nylon 6 sheath to the core of the polymer. Polypropylene. The yarn was stretched and textured in a continuous process, resulting in a yarn of 58 filaments and 1100 denier. East The yarn was wired and thermosetted (autoclaved) and formed into tassels on a carpet as described in Example 1. The physical properties of the yarn and carpet are noted below in Table 1.

Example 3 (invention) Example 2 was repeated, except that the weight ratio of nylon 6 to polypropylene was 80:20.

Example 4 (invention) Example 2 was repeated, except that the weight ratio of nylon 6 to polypropylene was 85:25.

Example 5 (invention) Example 2 was repeated, except that the weight ratio of nylon 6 to polypropylene was 70:30.

Example 6 (comparative) A 100% nylon 6 yarn (BS700F from BASF Corp) with 56 modified trilobal fibers was extruded at a polymer temperature of 275 ° C and stretched in one step. The winding speed was 1600 meters per minute. In a separate step, the yarn was textured using steam. Two of these threads were wired together with 4.5 twist per inch "S" twist on a twisting machine. cable. The skeins of these yarns were thermosetted in a steam autoclave with a maximum thermosetting temperature of 130 ° C. The yarn was then formed into tassels in a 1/8 caliber carpet tassel machine at a pile height of 1.27 cm and weights of 709 and 1134 grams / 0.836 square meters. The resulting carpet was then stained to a light brown color in a range of continuous staining.

Example 7 (invention) Example 6 was repeated, except that the yarn has a core of 20% by weight of polyethylene. The temperature of the polymer used for the polyethylene was 190 ° C before the introduction to the formation of the spindle with the polymer.

Example 8 (invention) Example 6 was repeated, except that the yarn has a core of 50% by weight of polyethylene. The temperature of the polymer used for the polyethylene was 190 ° C before the introduction to the formation of the use with the polymer. Examples 6-8 were all processed well and carpets were produced. Example 8, however, presented a mottled appearance after continuous staining. The physical data of the yarns and rugs of Examples 6-8 are shown below in Table 2.

Table 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex.

Single wire not wired Measured linear density (denier) 1277 1247 1274 1234 1128 Elongation to rupture (%) 43.7 42.8 41.7 41.5 41.5 Tenacity (g / denier) 2.90 2.70 2.65 '2.52 2.52 Module § 5% extension (g / denier) 4.79 4.73 5.62 5.60 5.26 Shrinking in boiling water 8.7 5.6 5.2 5.1 4.6 (*) Thread not thermosetted Denier linear measured 1557 1437 1384 1381 1269 Shrinking in autoclave ('*) 18.0 13.2 7.9 10.6 11.1 Vattermann drum carpet (5000 cycles): (a) Visual determination 3.5 4 4 3.5 3.5 (b) Retention of the height of 97 96 97 96 97 hair (%) Static Compression 96 90 95 94 94 Table 2 Ex. 6 Ex. Ex. 8 Single wire not wired Measured linear density (denier) 1434 1415 Elongation to rupture (%) 66 54 Tenacity (g / denier) 1.76 1.13 Module I 5% extension (g / denier) 5.57 5.52 Shrinkage in boiling water (%) 6.1 5.4 3.9 Straight wire, not thermo-hardened Linear Denier measured (two ends' 2683 2659 Non-hardened thermo-hardened wire Measured linear density - single 2908 2944 2678 (denier) Shrinkage in autoclave (%) 7.7 9.7 Carpets Vattermann drum (5000 cycles): (a) Visual determination 3.5 3 3 (b) Retention of the height of 89 90 90 Vattermann drum (22000 cycles): (a) Visual determination 1.5 1 1 (b) Height retention 87 84 84 hair (H) Static compression ('i) 95 93 88 Example 9 (invention) Dry nylon (BSF700F from BASF Corp) and polypropylene granules (melt index = 11) were loaded into a small bicomponent yarn forming unit to obtain 75% nylon by weight and 25% by weight propylene. The currents of the respective polymers were kept separate until they reached the row containing the etched plate. The melted nylon and polypropylene flows were extruded at 275 ° C to form trilobal bicomponent fibers with 114 nylon sheath and polypropylene core. The fibers were collected during spinning at 500 m / min. Numerous coils were combined in a short fiber line, stretched from 2.8 to 3.2 X, crimped in a filling machine and cut into short lengths of 20 cm (200,000 denier, stretched at 100 m / min). The short fiber became twisted yarns of 5.25Z and 4.5S, and the yarn was twisted into yarns for 3.00 / 2 cotton count carpet.

Wire twisted yarns have a rough construction compared to common 100% nylon yarns which is desirable in some end-use applications. The yarns representing two separate short fiber runs from the same spinning process were tested for their physical properties with the results shown in Table 3 below.

Example 10 (comparative) Example 9 was repeated, except that the nylon was present in an amount of 60% by weight and the polypropylene was present in an amount of 40% by weight. The threads representing two separate short fiber runs from the same spinning process were tested for their physical properties with the results shown in the following Table 3.

Example 11 (invention) Example 9 was repeated, except that 12% by weight of CaCO3 is dispersed in the polypropylene core. The physical properties for a representative thread appear below in Table 3.

Example 12 Example 11 was repeated, except that 25% by weight of CaCO- is dispersed in the polypropylene core. The thread of this example was not tested on its physical properties. Table 3 Ahem. 9 Axis 10 Axis 11 Proce Process Proce 1 s 2 s 2 s 1 or 2 Denier (g / filament) 22.3 22.1 23.8 23.0 23.3 curls / inch 6 n / a 7 n / an / a load (g) 61 69 72 58 54 Elongation (== ) 85 130 106 97 115 Tenacity (g / denier) 2.6 3.1 3.0 2.5 2.4 Module § 5% extension 9 11 9 11 9 (g / denier) Shrinkage in water 4.3 n / a 2.4 n / a n / a in boiling Although the invention has been described in relation to what is currently considered the most practical and preferred embodiment, it should be understood that the invention is not limited to the described modality, on the contrary, this proposal to cover the various modifications and equivalent arrangements that are included within the spirit and scope of the appended claims.

Claims (13)

1. CLAIMS 1. A bicomponent fiber having different cross-sections of melt spinning, which contains a fiber-forming polyamide domain, which constitutes at least 70% by weight of the fiber and a fiber-forming polyolefin domain that constitutes less than about 30% by fiber weight.
2. 2. The fiber of claim 1, in the form of a multi-lobed fiber for carpet.
3. 3. The fiber of claim 1, wherein the polyolefin domain is a linear polypropylene or polyethylene.
4. 4. The fiber of claim 1, wherein the polyolefin domain includes a particulate filler material dispersed therein.
5. 5. The fiber of claim 4, wherein the filler material is calcium carbonate.
6. 6. The fiber of claim 1 in the form of a trilobal fiber, for carpet.
7. 7. The fiber of claim 1, in the form of a continuous or short fiber.
8. 8. The fiber of claim 1, in the form of a bicomponent sheath-core fiber, wherein the polyamide domain occupies the sheath of the fiber and the polyolefin domain occupies the core of the fiber.
9. 9. The fiber of claim 8, in the form of concentric bicomponent core-sheath fiber.
10. 10. A carpet yarn composed of the fibers of any of claims 1-9. The yarn for carpet, according to claim 10, having less than about 75% shrinkage by thermosetting in comparison with the thermoset shrinkage of a carpet formed of 100% nylon fibers. A carpet comprising a bottom fabric and tassels formed of the carpet yarn according to claim 10 attached to the bottom fabric. 13. A method for making a bicomponent fiber comprising directing the respective molten fluids of a polyamide and a fiber-forming polyolefin to a spinneret, forming the bicomponent fiber by co-extruding the molten fluids of polyamide and polyolefin through the fibers. orifices of the row so that the polyamide is present as a domain constituting less than about 30% by weight of the fiber and the polyolefin is present in another domain constituting at least 70% by weight of the fiber, and then of this the tempering of the bicomponent fiber. 4. The method according to claim 13, which further comprises the dispersion of a material of particulate filler in the molten polyolefin fluid before the step of forming a bicomponent fiber by co-extruding the molten fluids of polyamide and polyolefin. 15. The method according to claim 14, wherein the particulate filler is calcium carbonate. 16. The method according to claim 13, wherein the polyolefin domain is a linear polypropylene or polyethylene. 17. The method, according to claim 13, comprises the formation of the bicomponent core-sheath fiber, wherein the polyamide domain occupies the fiber sheath and the polyolefin domain occupies the core of the fiber. 18. The method, according to claim 17, comprises the formation of the bicomponent concentric-sheath fiber. 9. A fabric containing the fibers according to any of claims 1-9.